Patent GB-664622-A (GB)
Title: Improvements in and relating to the generation of electric pulses
Inventor: LEVY MAURICE MOISE
IPC: H03K3/543
Filed: 1949-04-26
Abstract: 664,622. Pulse circuits; multiplex pulse signalling. GENERAL ELECTRIC CO., Ltd. April 13, 1950 [April 26, 1949], No. 11090/49. Classes 40 (v) and 40 (vi). A train of pulses is delayed with respect to a train of regularly recurring master pulses by applying each of the master pulses to generate two sine-wave voltages which are harmonically related to each other and to the repetition frequency of the master pulses, the sinusoidal voltages are then combined to produce a composite wave which is applied to shock-excite a tuned circuit thus producing an output pulse coincident in time with that part of the composite wave which has the highest rate of change of amplitude with time. Fig. 1 shows the application to the receiver and demodulator of a position modulated pulse multiplex system in which the synchronizing signal comprises two closely spaced pulses located at the commencement of the first channel, Fig. 2 (not shown). The incoming signals are applied via transformer 12 to the last I.F. amplifier valve 10, the tuned output transformer 14 of which is connected via a diode rectifier 16 and low-pass filter 17 back to the control grid circuit of valve 10 so that the demodulated signal is also amplified in this stage which functions as a reflex circuit. The demodulated signal across load 18 is applied to the control grid of amplifier 20 to produce an amplified signal across load resistor 24 which is fed via capacitor 25 to a demodulator circuit of the type described in Specification 664,653. The anode load of valve 20 also comprises a transformer 23, the secondary winding of which is tuned to the recurrence frequency of the pair of pulses in each synchronizing signal. The tuned circuit 27, 28 is lightly damped by resistor 32 and is shockexcited by each synchronizing and channel pulse the damped wave trains produced by the double synchronizing pulse reinforcing each other to produce a large amplitude pulse, Fig. 3 (not shown), which alone is passed by the biased diode 30. The pulse initiated by the synchronizing signal is amplified in valve 31 the anode circuit of which comprises two tuned circuits 48, 49 and 50, 51 which are tuned to the recurrence frequency and twice the recurrence frequency of the synchronizing signals respectively and a coupled tuned circuit 52, 53 which is also tuned to the recurrence frequency of the synchronizing signals. The three circuits are maintained in oscillation by the pulses applied to valve 31 and the outputs from any two of them may be added and selected by operation of switch arm 75 to give a composite wave which has a point of maximum slope located according to the setting of the switch, Figs. 4-7 (not shown), since it is dependent upon the relative phase relationships between the sinusoidal voltages produced across the tuned circuits. The composite wave selected by switch arm 75 is applied via valve 77 to shock-excite tuned circuit 81 which has a resonant frequency very much higher than the fundamental frequency of the composite oscillation so that each time the composite wave passes through its region of maximum slope the circuit 81 is shock-excited to produce a damped oscillation. The points of maximum slope of the composite waves produced from tuned circuits 48, 49, 50, 51 and 52, 53 are such that the switch arm 75 enables pulses to be produced across tuned circuit 81 which are either in step with the synchronizing signal or progressively delayed relatively to the synchronizing signal by one channel width. The first negative pulse from tuned circuit 81 causes diode 83 to conduct and discharge capacitor 84 and the next positive-going pulse renders diode 87 conducting to charge capacitor 88, which causes diode 89 to conduct and thus transfer the charge from capacitor 88 to capacitor 84. This transference continues until the next channel pulse from valve 10 renders diode 90 conducting and discharges capacitor 88. Thus, if switch arm 75 is set, say to position 54, capacitor 88 commences charging at the start of channel 1 and is discharged by the signal pulse in channel 1 so that the amplitude of charge transferred to capacitor 84 is a function of the position of the signal pulse in channel 1 and the amplitude modulated pulses then have their intelligence subtracted in the conventional manner. The channel fed to speaker 92 is thus dependent upon the setting of switch 56.